Week 9 - Decision Theory Flashcards
How do you track decisions?
Decision log
- Who
-When
- Why
Routine Decision
- small impact
- Reversible
- short term
- data available
- standard decision process
Make-or-break decision
High impact
irreversible
long term
safety or product liability is critical
no well defined decision process
Structured decision processes
- Qualitative
- Quantitative
How is risk described?
A - Future Event
C - Activity consequence
C* - Prediction of C
U - Uncertainty about what value C will take
P - probability given K
K - background information
Risk analysis methods
- Simplified (Qualitative )
- Standard (Quantitative or qualitative)
- Model-based (primarily quantitative)
simplified risk analysis
informal procedure using brainstorming and discussion
Standard Risk analysis
Formalized procedure where recognized risk analysis methods are used.
Risk matrices are often used.
Model-based risk analysis
Makes use of techniques such as event tree and fault tree analysis.
Fault Tree Analysis (FTA)
System analysis techniques used to determine the root causes and probability of occurrence of a specified undesired event.
OR gate probability
P(A U B) = P(A) + P(B) - P(A)P(B)
OR gate probability for mutually exclusive events
P(A U B) = P(A) + P(B)
OR gate with 3 inputs Probability
P(A+B+C) = P(A)+P(B)+P(C) - P(A)P(B)-P(A)P(C)-P(B)*P(C) + P(A)P(B)P(C)
AND Gate probability
P(A ∩ B) = P(A)P(B)
Cut sets
Sets of Events that together cause the top undesired event to occur.
What does a low-order cut set indicate?
High safety vulnerability
Reactive FTA
Used after an accident as an investigation method
